There are several reasons why the glass might have cracked on a wood-burning stove, but all of the many reasons can be separated into two main causes:
Let’s explore both of those groups in more detail.
As you might have guessed, impact damage to your stove glass is caused by something coming into contact with your glass more forcefully than it should. The most common examples of this are:
- Overloading the firebox with fuel, then inadvertently closing the door onto a protruding log.
- Hitting the glass from the outside. For instance, banging the hoover into it or dropping/throwing something that hits the glass.
- Over-tightening screws and bolts holding the glass in place. The impact of an overtightened screw can cause the glass to crack, especially once the stove is up to temperature and the glass expands slightly.
Keep in mind that, even though you might not see the crack straight away, it is possible that the glass is weakened or that a hairline crack that is not yet visible to the naked eye has been caused. Once the stove is operating at a high temperature, the crack might worsen.
Cracks that are caused by usage or, perhaps more accurately, misusage are those that are due to the way that the stove was being operated. Some of the main causes of misusage causing stove glass to crack are:
- Overfiring. This is when the stove is being operated at too hot a temperature. This could be because there is too much fuel in the stove or because too much oxygen is being allowed into the firebox. Ironically, once the glass is cracked, extra oxygen inevitably gets into the stove, which causes even more overfiring. That’s why it is important to replace your stove glass when you first notice a crack.
- Burning household coal. Standard household coal is fine to burn on open fires, but it is quite a volatile fuel. Within the confined space of a stove, this can lead to mini-explosions, which are forceful enough to crack the glass. Find out more about why your shouldn’t burn household coal on a stove.
- Burning pet coke. Burning petroleum-based fuels – whether deliberately or because your fuel supply has because mixed with pet coke – is also likely to cause explosions in the firebox than will cause the stove glass to break.
Avoiding cracked stove glass
The best way to ensure you don’t crack the glass on your wood-burning stove is to take care when adding fuel, only burn the required amount and only burn the types of fuel recommended in your stove manual.
If the glass on your stove is currently cracked, the good news is that it is relatively inexpensive and quite easy to replace.